Operator&#39;s seat supporting device for service vehicle

ABSTRACT

An operator&#39;s seat ( 6 ) is mounted via a posture adjusting mechanism ( 40 ) on a supporting plate ( 3 ) supported by at least two damper cylinders ( 50, 30 ) at a place where an operator&#39;s seat is installed, and at least one of the damper cylinders ( 50, 30 ) is used as a damper cylinder ( 50 ) for reducing vibrations by making use of a magnetic rheological fluid.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an operator's seat supporting devicefor a service vehicle having a variable damping mechanism providedmainly in an operator's cabin of a construction machinery and capable ofimproving the availability.

2. Description of Related Art

The conventional type of supporting device for an operator's seatprovided in an operator's cabin of a construction machine such as ahydraulic shovel or a bulldozer receives a larger shock delivered to theseat on which the operator sits as compared to that delivered to anoperator's seat in a general industrial vehicle, and there have beenproposed various measures for a suspension structure for reducing theshock.

As a suspension structure for an operator's seat in this type of servicevehicle, there has been known one, for instance, as shown in FIG. 9A andFIG. 9B. In this suspension structure, an X-shaped link 102 with thelink members crossing each other in the longitudinal direction andlinked to each other with a pin 103 at a crossing point on a base member101 are provided with a prespecified space in both right and left sidesthereof, and a link 110 with the height adjustable is provided betweenthe right and left X-shaped links 102, 102.

In the X-shaped link 102, a base edge of one link member 102 a ispivotably connected to the base member 101 with the other edge connectedto a seat mounting base frame 104 with a pin 105, and a lower edge ofanother link member 102 b can move on the base member 101 with the upperedge connected to the seat mounting base frame 104 with a pin 106, andthe cushioning capability is provided by a suspension cylinder 107.

The height-adjustable link 110 is rolled in the state in which a roller111 provided at a lower edge thereof is engaged with a guide rail 108provided on the base member 101 with an upper edge thereof linked to anedge of a coil spring 112 on the seat mounting base frame 104 so thatthe tension is energized in the erecting direction, and further anadjustment knob 113 capable of adjusting the weight and height bydisplacing the link 110 in the vertical direction by means of adjustingtension of the spring 112 is provided therein. In the figures, thereference numeral 115 indicates a seat, and the reference numeral 116indicates a suspension cover.

Reference 1 (Japanese Patent Laid-Open Publication No. HEI 9-209406)discloses a suspension structure in which a forward section thereof issupported with a rubber spring system which elastically deforms littlein the vertical direction, and a rear section thereof is supported by acoil damper unit system which elastically deforms largely in thevertical direction. In addition, a suspension mechanism for an operatingseat using the X-shaped link is disclosed, for instance, in Reference 2(Japanese Patent Laid-Open Publication No. HEI 11-280117).

However, with the supporting means for an operator's seat employing theX-shaped link 102 as used in the conventional technology, the link 102occupies a space under the seat 115, which narrows a space under theoperator's feet.

Further there is another disadvantage that a damper is providedexternally, which disables effective utilization of the space.

In addition, the X-shaped link is generally made from flat steel bars,so that the rigidity in the lateral direction is disadvantageously low,and as the joint section includes a pin, and therefore there is anotherdisadvantage that it is difficult to insure strength against load.

As the mechanism for adjusting a body weight is integrated with that foradjusting the height, it is difficult to achieve the complete balancebetween an operator's body type and the operator's body weight.

Namely, when an operator is a person not having the standard body typesuch as a relatively heavy person having the low seating height or aperson having the relatively high seating height against the bodyweight, if a seat height is adjusted to the operator's posture, thebuffering function is disadvantageously lost, which is another problem.

In the suspension seat structure as disclosed in the cited reference 1,as dampers having different structures respectively are provided in thefront of and at the back of the seat, and the dampers are required to beadjusted discretely, and in addition the damper provided at the back ofthe seat is attached to an outer side of a backrest of the seat, sothat, when an inclination of the backrest is changed, the bufferingeffect also varies, which is disadvantageous from a view point ofstructure and not preferable because of its complicated structure.

The suspension device in the operator's seat device disclosed in thecited reference 2 also has the problems as described above.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an operator's seatsupporting device for a service vehicle with a compact suspensionmechanism with improved functions and capable of ensuring operator'scomfortable posture during the operation.

In an operator's seat supporting device for a service vehicle accordingto an aspect of the present invention, at least biaxially supported bydamper cylinders each are arranged along an axial line parallel to avertical line passing through a shoulder of an operator sitting on aseat, and the operator's seat supporting device includes a postureadjusting mechanism provided by the sections supported by the dampercylinders and the seat.

In an operator's seat supporting device for a service vehicle accordingto another aspect of the present invention, an operator's seat ismounted via a posture adjusting mechanism on a supporting platesupported by at least two damper cylinders at a place where anoperator's seat is installed, and at least one of the damper cylindersreduces vibrations by making use of a magnetic rheological fluid.

Preferably, with the above operator's seat supporting device for aservice vehicle, in the damper cylinder for reducing vibrations bymaking use of the magnetic rheological fluid, a buffering cylinder and acontrol cylinder for controlling vibrations with the magneticrheological fluid may be monolithically formed.

Preferably, with the operator's seat supporting device for a servicevehicle, the damper cylinder may have a biaxial slide supportingstructure, and a coil spring may be provided in the inner side or in theouter side from a shaft body having dual-shafts.

Preferably, with the operator's seat supporting device for a servicevehicle, an operator's seat rotating mechanism may be provided on thesupporting plate supported by the damper cylinders.

With the configuration as described above, an area occupied by a seatsupporting section on a floor surface can be reduced, whereby a widespace can be provided under an operator's feet to secure that theoperator can take a comfortable posture during the operation.

Further there is also provided the advantage that a floor surface of theoperator's cabin can easily be cleaned.

With the configuration as described above, in addition to the advantagesdescribed above, there is provided the advantage that the heightadjustment of the seat can be carried out independently from adjustmentof a body weight of an operator sitting thereon with the optimal heightprovided to secure that the operator can take a more comfortable postureduring the operation. Further by making use of a magnetic rheologicalfluid, a vibration damping force can variably be set according to changeof the magnetic field, and a damping force can previously be setaccording to an operator's body weight, which advantageously improvesthe buffering effect against a shock by an external force.

When the configuration as described above is employed, the structure iscompact, so that a space required for installation thereof can bereduced, so that the occupied space under operator's feet can beminimized to secure that the operator can take a comfortable postureduring the operation.

With the configuration described above, a damper cylinder functioning asa supporting body has a biaxial slide structure, so that only a furthersmall space is required, and a load is shared by a plurality of dampercylinders, so that the stable supporting force can be obtained withoutcausing any saccadic movement.

Further with the configuration described above, a rotating mechanism isprovided on a supporting plate supported by the damper cylinder, so thata rotating movement can be carried out without spoiling the bufferingfunction of the seat.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevational view showing a first embodiment of anoperator's seat supporting device for a service vehicle according to thepresent invention;

FIG. 2 is a side elevational view of FIG. 1;

FIG. 3 is a longitudinal cross-sectional view showing a damping functioncontrol mount;

FIG. 4 is a cross-sectional view showing the primary portion of thedamping function control mount cylinder;

FIG. 5 is a longitudinal cross-sectional view showing a supportingdamper;

FIG. 6 is a cross-sectional view showing a second embodiment of adamping function control mount cylinder;

FIG. 7 is a cross-sectional view showing the primary portion of thedamping function control mount cylinder according to the secondembodiment;

FIG. 8 is a cross-sectional view showing a third embodiment of a dampingfunction control mount cylinder;

FIG. 9A is a side elevational view showing an embodiment of a supportingstructure for an operator's seat based on the conventional technology;and

FIG. 9B is a view showing the operator's seat based on the conventionaltechnology viewed from the front side.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT(S)

Embodiments of an operator's seat supporting device for a servicevehicle according to the present invention is described below withreference to the related drawings.

First Embodiment

FIG. 1 is a front elevational view showing a first embodiment of theoperator's seat supporting device for a service vehicle according to thepresent invention; FIG. 2 is a side elevational view of FIG. 1; FIG. 3is a longitudinal cross-sectional view showing a damping functioncontrol mount; FIG. 4 is a cross-sectional view showing the primaryportion of the damping function control mount cylinder; and FIG. 5 is alongitudinal cross-sectional view showing a supporting damper.

An operator's seat supporting device 1 according to this embodimentincludes two damper cylinders 50, 30 erecting from and provided on afloor surface 2 of an operator's cabin with a prespecified space; aposture adjusting section 40 provided on a movable supporting plate 5disposed via a rotating mechanism 4 on a supporting plate 3 supported bythese damper cylinders 50, 30; and an operator's seat 6 mounted via thisposture adjusting section 40.

Of the damper cylinders 50, 30, one is a damping function control mount50 (described simply as a damper cylinder 50 hereinafter) having amagnetic rheological fluid control function, and the other is a dampercylinder 30 for supporting (supporting damper).

The damper cylinder 50 having a magnetic rheological fluid controlfunction includes, as shown in the cross-sectional view in FIG. 3, abuffering cylinder 53 externally and coaxially engaging a fixed member51 having a mounting base 52 against the floor surface 2 (correspondingto the biaxial slide support structure according to the presentinvention), a coil spring 59 for restoring a damper provided inside thefixed member 51, and a control cylinder 60 for a magnetic Theologicalfluid associated with the buffering cylinder 53 and capable ofcontrolling operations of the buffering cylinder 53, and a mounting baseplate 58′ for mounting the supporting plate 3 thereon is provided on atop of the buffering cylinder 53.

The buffering cylinder 53 is a tubular cylinder including a movablemember 54 provided outside and the fixed member 51 provided inside andcoaxially engaged therewith.

The movable member 54 is so connected that a male screw 54 b formed onan external peripheral surface of an upper end of the cylinder member 54a is screwed to a female screw 54 d formed on an internal peripheralsurface of a drooping spherical base section 54 c. Further, a femalescrew 54 e is formed on an inner peripheral surface of a lower end ofthe cylinder member 54 a, to which a cover member 54 f with a male screwformed is screwed.

An internal capacity of the cylinder is controlled to a prespecifiedvalue by the cylinder member 54 a, the base section 54 c and the covermember 54 f.

The buffering cylinder 53 is slidably assembled with the fixed member 51with a circular projection 55 functioning as a piston integrallyprovided at an intermediate section of the fixed member 51, and a sealring 55 b is engaged in a groove section 55 a formed on an outerperipheral surface of the circular projection 55 and contacts aninternal surface of the movable member 54 (cylinder member 54 a) with afirst chamber 56 a and a second chamber 56 b defined vertically.

Incidentally, the internal peripheral surface of the cylinder member 54a located at an upper edge section of the first chamber 56 a isprojected in a ring-shaped manner, and a seal ring 56 c is fitted to agroove formed at the tip end thereof. Further, the screwing portion ofthe cover member 54 f located at a lower edge section of the secondchamber 56 b is formed cylindrical, and seal rings 56 d and 56 e arefitted to grooves formed on upper and lower sides of the internalperipheral surface thereof. With the use of the seal rings 56 c, 56 dand 55 b, the sealability of the first chamber 56 a and the secondchamber 56 b is secured. Additionally, the seal ring 56 e inhibits thedust entering from the outside.

The control cylinder 60 includes a cylindrical main body 61, an uppercover member 63 and a lower cover member 63′ that cover holes 62 openingat the upper and lower part of the cylindrical main body 61.

An insert body 64 is provided inside the cylindrical main body 61 on thecenter line of the cylindrical main body 61, the upper and lower edgesof the insert body 64 is joined and fixed to the cylindrical main body61 as well as to the lower cover member 63′.

The insert body 64 includes a clearance forming section 64 a made of amagnetic material such as electromagnetic soft iron, and a shaft 64 bmade of a non-magnetic material such as stainless, the shaft 64 bpress-fitted to the upper and lower edges of the clearance formingsection 64 a.

On the other hand, as shown in FIG. 4, a bobbin 61a made of anon-magnetic material is embedded on an inner peripheral surface of thecylindrical main body 61 corresponding to the position of the clearanceforming section 64 a. A coil 61 b with a lead wire being winded isprovided around the bobbin 61 a, the end of the lead wire beingconnected to a controller provided at the outside of the damper cylinder50. The bobbin 61 a and the coil 61 b function as an electromagneticcontrol section that controls the viscosity of the magnetic rheologicalfluid flowing through the cylinder.

Two connecting holes 65 are formed at the upper and lower parts of alateral surface of the cylindrical main body 61 to communicate theinside and the outside thereof, and the connecting holes 65 arerespectively connected to two connecting holes 54 g penetrating theinside and the outside of the cylinder member 54 a via a cylindricalconnecting member 66. It is to be noted that the one of connecting holes54 g is connected to the first chamber 56 a while the other one isconnected to the second chamber 56 b.

Further a buffering chamber 67 is provided below the upper cover member63, so that expansion of the magnetic rheological fluid to be sealedtherein due to temperature change can be accommodated.

When the insert body 64 is installed in the cylindrical main body 61, asshown in FIG. 4, the interior of the cylindrical main body 61 is dividedinto the upper side chamber 62 a and the lower side chamber 62 b byinterposing the clearance forming section 64 a, thereby forming a spaceS between the inner surface of the cylindrical main body 61 and theouter surface of the clearance forming section 64 a. The space Sfunctions as a restrictor for adjusting the fluid flow rate flowingbetween the upper side chamber 62 a and the lower side chamber 62 b.

A magnetic rheological fluid (such as, for instance, iron carbonylparticles suspended in mineral oil as a carrier) is filled in each ofthe control cylinder 60 and the buffering cylinder 53 each having theconfiguration as described above.

In contrast to the damper cylinder 50 as described above, the dampercylinder 30 for supporting includes, as shown in FIG. 5, a fixed member31 having a column-like form with a mounting base 32 attached at a loweredge thereof, a tubular movable member 34 engaged with this fixed member31 and having a base plate for mounting the supporting plate 3 thereon;and a coil spring 37 provided concentrically with the lower edgesupported by a top surface of a bottom edge member 31 a of the fixedmember 31 and also the upper edge thereof contacting an internal bottomsurface of a mounting cap member 35 of the movable member 34.

The fixed member 31 has the structure in which the bottom edge member 31a which is a tubular body having prespecified dimension and closes thelower edge section of the fixed member 31 is attached, and the mountingbase 32 is monolithically attached to this bottom edge member 31 a withthe upper edge section opened.

A circular member 34 a is monolithically attached to an upper edgesection of the movable member 34, and the cap member 35 is screwed intoan upper edge section of this circular member 34 a to close the uppersection. Monolithically attached to a top surface of this cap member 35is a mounting base plate 38 for supporting the supporting plate 3.

Bearings 36, 36′ are monolithically attached to an internal peripheralsurface of the circular member 34 a of the movable member 34 and aportion 34 b thereof with the internal peripheral section of the loweredge section having a smaller diameter respectively so that the fixedmember 31 can be slid in the vertical direction without losing theconcentric positional relation thereto.

As shown in FIGS. 1 and 2, the damper cylinders 50, 30 having theconfiguration as described above respectively are provided in theerecting state on a floor surface of the operator's cabin so that thecenter line is substantially aligned to a vertical plane (vertical lineC) passing through a shoulder Q′ of an operator Q when the operator Qsits on the seat 6 with the normal posture with the mounting bases 52,32 attached to the damper cylinders 50, 30 respectively. These twodamper cylinders 50, 30 support the supporting plate 3 having adimension slightly larger than the width of a seat plate section 6 a ofthe seat 6.

With the configuration as described above, the operator Q sitting on theseat 6 is supported by the damper cylinders 50, 30 at a position on aline passing through a gravity center or a position close to the gravitycenter of the operator Q, so that, although the operator Q is supportedby two damper cylinders, vibrations in the longitudinal direction andthose in the lateral direction do not occur, and the seat 6 is securelysupported with the simple supporting structure.

A swivel ring (rotating mechanism 4) is provided with the shaft centerpositioned at a central position of a line connecting centers supportedby the damper cylinders 50, 30 on the supporting plate 3, and themovable supporting plate 5 is attached thereto with a supporting member4 b attached to the swivel ring so that the swivel ring can freelyswivel.

Slide mechanisms 41 each for adjusting an operator's position in thelongitudinal direction as a posture adjusting section 40 and a heightadjusting mechanism 42 are provided on the movable supporting plate 5,and the seat 6 is attached thereto via the height adjusting mechanism42.

The slide mechanisms 41 each extending in the longitudinal direction arearranged with a prespecified space in the lateral direction, and amounting base member 7 of the seat 6 is supported by the movable member.The slide mechanism 41 has a known structure, and a movable member canintermittently move in the longitudinal direction thereon along a railso that a position of the operator Q in the longitudinal direction canbe adjusted.

The height adjusting mechanism 42 having a known structure is providedon the mounting base member 7, and a seat plate section 6 a of the seat6 is attached with a known means to a seat mounting frame body abovethis height adjusting mechanism 42. The height adjusting mechanism 42employed in the present invention can adjust a position in the verticaldirection with cross links. It is to be noted that also the heightadjusting mechanism 42 not employing the cross links may be used in thepresent invention.

The reference numerals 8 and 8′ each indicate a console in which anoperating lever or other operating sections of machines and equipmentsare accommodated, and this console 8 is monolithically attached with abracket to the mounting base member 7, and can move in the verticaldirection and swivel together with the operator's seat 6 to allow foroperations without requiring an operator to change the positionalrelation therewith. The reference numeral 6 b in the figure indicates abackrest.

The operator's seat supporting device 1 according to this embodiment isinstalled in an operator's cabin (not shown) of a service vehicle, andsupports the operator's seat 6 as described above.

The operator's seat supporting device 1 having the configuration asdescribed above according to this embodiment can set an operator'sposition in the longitudinal direction with the slide mechanisms 41 andthe operator's height with the height adjusting mechanism 42respectively, when the operator adjusts the operating posture.

The two damper cylinders 50, 30 are balanced with the energizing forcesof the coil springs 59, 37 respectively in the normal state to supportthe operator's seat 6.

Vibrations due to a shock or any other load from the outside during theoperation are damped by the two damper cylinders 50, 30 supporting theseat 6, and one damper cylinder 50 has a function for controllingattenuation with an electromagnetic control section with a magneticrheological fluid included therein, and with the configuration asdescribed above, a signal from a sensor for detecting vibrationspreviously installed in an operator's cabin or on a machine frame isreceived by the controller, and a current is flown at a required rate tothe coil 61 b of the control cylinder 60 according to an output signalgenerated by comparing the received signal to preset data, so that thevibrations are quickly damped by controlling the pressure differencegenerated between the first chamber 56 a and the second chamber 56 b inthe buffering cylinder 53 from the control cylinder 60, thus thevibration-controlling function being provided.

The other damper cylinder 30 has the function for dampening a shock byfollowing the vibration controlling and buffering function of the dampercylinder 50 with a cushioning function with the coil spring 37 with themovable member 34 against the fixed member 31 provided therein.Therefore, even when a large shock is applied thereto, vibrations canquickly be absorbed and dampened.

As for the vibration controlling action by the damper cylinder 50, whenvibrations are delivered from a vehicle's body, the movable member 54displaces against the fixed member 51 in the axis line direction. Whenthe movable member 54, for example, moves in the downward direction ofthe vertical direction against the energizing force by the coil spring59,the cylinder member 54 a of the movable member 54 acts to push downthe magnetic Theological fluid in the first chamber 56 a.

As shown in FIG. 4, the magnetic Theological fluid in the first chamber56 a is pushed out into an upper side chamber 62 a of the controlcylinder 60 through the connecting hole 54 g, the connecting member 66and the connecting hole 65 by pushing down action of the magneticrheological fluid. In this step, a reduced pressure state is generatedin the second chamber 56 b of the buffering cylinder 53, so that themagnetic Theological fluid is fed from a lower side chamber 62 b of thecontrol cylinder 60 through the connecting hole 65, the connectingmember 66 and the connecting hole 54 g into the second chamber 56 b.

When the magnetic Theological fluid in the first chamber 56 a is movedinto the upper side chamber 62 a of the control cylinder 60 inassociation with the downward movement of the movable member 54 in thebuffering cylinder 53, the pressure of the second chamber 56 b isreduced, so that the pressure of the lower side chamber 62 b of thecontrol cylinder 60 communicating the second chamber 56 b through theconnecting hole 65, the connecting member 66 and the though hole 54 g isalso reduced.

Therefore, the upper side chamber 62 a of the control cylinder 60 entersthe pressurized state, while the lower side chamber 62 b enters thereduced pressure state, so that the magnetic rheological fluid filled inthe upper side chamber 62 a flows toward the lower side chamber 62 b dueto the pressure difference.

In this step, a flow rate of the magnetic rheological fluid isrestricted at the space S between the outer surface of the clearanceforming section 64 a and the inner surface of the cylindrical main body61, the space S separating the upper side chamber 62 a from the lowerside chamber 62 b.

A vibration signal indicating vibrations of the fluid passing throughthe space S is sent from the sensor (not shown) to the controller, andthe coil 61 b is energized at a prespecified current rate based onpreset data so that the magnetic field corresponding to the current isgenerated between the clearance forming section 64 a made of a magneticmaterial and the cylindrical main body 61 with the flowing magneticTheological fluid magnetized, thereby the magnetic rheological fluidbeing magnetized to change the viscosity. In other words, fluidity ofthe magnetic Theological fluid changes in proportion to intensity of themagnetic field.

When the movable member 54 moves in the upward direction, the magneticTheological fluid flows between the control cylinder 60 and thebuffering cylinder 53 in the direction reverse to that in the operatingsequence described above with the flow state controlled.

By changing the flow state of the magnetic rheological fluid asdescribed above to change the flow resistance of the magneticrheological fluid in flowing, the movement speed in the verticaldirection of the buffering cylinder 53 is controlled to dampen a shockloaded thereto.

In a case of an operator's seat in an operator's cabin provided in abulldozer, when a large shock such as that experienced in running over alarge rock or a projection, for instance, when a vehicle moves backwardis loaded thereto, for dampening the vibrations caused by the shock,with the use of the above-described electromagnetic control section inthe control cylinder 60, by raising a rate of a current loaded from thecontroller to a level higher than that in the normal state to raise theintensity of a magnetic field generated between the cylindrical mainbody 61 and the clearance forming section 64 a proportionately, theapparent viscosity of the magnetic rheological fluid flowing through thespace S is made larger with the flow resistance at space S raised, sothat the flow velocity of the movable member 54 is reduced.

In other words, the cushioning function of buffering a sudden and heavyshock with a soft buffering action provided by a soft spring action andalso suppressing vibrations occurring after the shock is loaded bygiving a damping force with the control cylinder 60 is achieved in thepresent invention as described above.

Against the small and successive shocks experienced when driving on anirregular ground surface, by sending a control signal in the directionfor lowering the intensity of a magnetic field from the controller tothe coil 61 b in response to a detection signal from the sensor to lowerthe magnetic flux density to the magnetic rheological fluid in thecontrol cylinder 60 with the electromagnetic control section, the flowresistance is reduced with the fluidity of the magnetic rheologicalfluid raised contrary to the case described above, so that a movementrate of the movable member 54 in the axial direction in the bufferingcylinder 53 is reduced, and therefore soft and smooth action fordampening vibrations is provided.

In contrast to the damper cylinder 50 having the functions as describedabove, the other damper cylinder 30 has a supporting function with asimple structure including the coil spring 37 for buffering therein, andperforms the supporting function in association with actions of thedamper cylinder 50 as a damper cylinder supporting the whole seat 6leaving a main portion of the vibration-controlling function fordampening vibration to the damper cylinder 50.

With the configuration, the seat 6 is smoothly buffered againstvibrations with the two damper cylinders 50, 30, thus comfortable andsmooth operations being insured to an operator.

As described above, the operator's seat supporting device 1 according tothis embodiment has the configuration in which vibrations are dampenedwith a vibration buffering device completely different and independentfrom the seat height adjusting mechanism 42, so that adjustment inresponse to an operator's body weight is not required, and the efficientbuffering function can be provided in the optimal state only by carryingout positional adjustment according to the operator's body type, therebythe operator performing required operations in the comfortable state.Further a wide space can be secured under an operator's feet, so thatthe problem of narrow space under the operator's feet as experienced inthe supporting device based on the conventional technology can beeliminated, whereby there is provided the advantage that an operator canperform various operations in a relaxed and comfortable posture.

Second Embodiment

Next, referring to FIG. 6, a second embodiment of the present inventionis described below.

In the present embodiment, it is only different from the operator's seatsupporting device I according to the first embodiment that the structureof the damper cylinder 50 (damping function control mount cylinder) ismodified. In the following, the description of the components have beendescribed already or that of the same components as the above-describedcomponents will be omitted or simplified.

The damper cylinder 10 according to the second embodiment having amagnetic Theological fluid control function includes, as shown in thecross-sectional view in FIG. 6, a buffering cylinder 13 externally andcoaxially engaging a fixed member 11 having a mounting base 12 againstthe floor surface 2 (corresponding to the biaxial slide supportstructure according to the present invention), a coil spring 19 forrestoring a damper provided inside the fixed member 11, and a controlcylinder 20 for a magnetic rheological fluid associated with thebuffering cylinder 13 and capable of controlling operations of thebuffering cylinder 13, and a mounting base plate 18′ for mounting thesupporting plate 3 thereon is provided on a top of the bufferingcylinder 13.

The buffering cylinder 13 is a tubular cylinder including a movablemember 14 provided outside and the fixed member 11 provided inside andcoaxially engaged therewith. The movable member 14 has a thick circularmember 14 b connected to and integrated with an upper edge section ofthe cylinder member 14 a and also has a circular head member 14 cscrewed into a lower edge section thereof, and controls an internalcapacity of the cylinder to a prespecified value with an internal loweredge of the circular member 14 b fixed to an upper edge section of thecylinder member 14 a and an internal upper edge of the head member 14 c.

The buffering cylinder 13 is slidably assembled with the fixed member 11with a circular projection 15 functioning as a piston integrallyprovided at an intermediate section of the fixed member 11, and a sealring 15 b is engaged in a groove section 15 a formed on an outerperipheral surface of the circular projection 15 and contacts aninternal surface of the movable member 14 (cylinder member 14 a) with afirst chamber 16 a and a second chamber 16 b defined in front and at theback thereof. A seal ring 16 d is engaged in each of the first chamber16 a and the second chamber 16 b to restrict the fluid from leaking fromthe inside of the cylinder.

Bearing bushes 17 guided by the fixed member 11 are provided in thecircular member 14 b and the head member 14 c each connected to themovable member 14 respectively, and with the bearing bushes 17 themovable member 14 can slide up and down being aligned with the centerline and also accommodate a load applied to the supporting plate 3 inthe stable state. Therefore the two bearing bushes 17, 17 shouldpreferably be arranged with a space between the two within a reasonablerange. A seal member 17′ is provided in the engaging state at an outerside from the engaging position of the bearing bush 17 so that thechambers 16 a and 16 b are water-tight against the outside. A cap member18 is screwed into the circular member 14 b at a top section of thebuffering cylinder 13 having the configuration as described above, and amounting base plate 18′ for mounting the supporting plate 3 thereon isattached to this cap member 18.

The control cylinder 20 has a hole 22 with a prespecified internaldiameter penetrating through a main body 21 with prespecified dimensionsin the vertical direction and also has an upper cover member 23 and abottom cover member 23′ provided to close two edge sections of thispenetrating hole 22. A supporting member consisting of a coil section 25and a sleeve 24 a is provided between the upper cover member 23 and thebottom cover member 23′, and the supporting member is so arranged thatthe coil section 25 is located at an intermediate position of thesupporting member supported by the sleeve 24 a made from a non-magneticmaterial with the upper and bottom sections engaged with the supportingmember.

A slight clearance “a” is formed between an internal peripheral surfaceof the main body 21 and an external peripheral surface of a bobbin 25 aof the coil section 25. A lead wire 27 extending over a controller notshown enabling electric control is connected to a coil 25 b of the coilsection 25, and the coil 25 b is attached to the bobbin 25 a made ofmagnetic material as the core of a wire-wound section of the coilsection 25 with the small clearance “a” defined and maintained betweenthe bobbins 25 a and an internal peripheral surface of the cylindermember 26 to form an electromagnetic control section causing a flowresistance of the magnetic Theological fluid. The main body 21 is madefrom an electromagnetic soft iron for example so that a magnetic fieldis strongly formed only in the range of the bobbin 25 a.

In the main body 21, connecting holes 28 a and 28 b communicating to thefirst chamber 16 a and the second chamber 16 b inside the cylindermember 14 a of the buffering cylinder 13 are provided with appropriatespaces from the cylinder member 26 respectively so that the magneticrheological fluid can flow from the control cylinder 20 to the bufferingcylinder 13. Further a buffering chamber 29 with gas such as the airincluded therein is provided at the top of the control cylinder 20 sothat expansion of the magnetic rheological fluid due to temperaturechange can be accommodated. A magnetic rheological fluid (such as, forinstance, iron carbonyl particles suspended in mineral oil as a carrier)is filled in each of the control cylinder 20 and the buffering cylinder13 each having the configuration as described above.

As shown in FIG. 7, the electromagnetic control section causing a flowresistance in the magnetic rheological fluid in the control cylinder 20includes a cylinder member of the control cylinder 20 and the coilsection 25 provided therein, and also includes a known controller notshown and connected with the lead wire 27 to the coil section 25. Thecoil section 25 is energized via the controller through the lead wire27.

The electromagnetic control section controls a signal from a sensor fordetecting vibration provided, for instance, in an operator's cabin notshown, and changes intensity of a magnetic flux generated between thebobbin 25 a and the main body 21 by flowing a prespecified rate ofelectric current to the coil section 25 according to an output signaltherefrom, so that the electromagnetic control section can increase orreduce the flow resistance by changing the apparent viscosity (fluidity)of the magnetic rheological fluid within the magnetic field when themagnetic Theological fluid flows through the narrow clearance “a” formedbetween the bobbin 25 a and an internal wall of the main body 21 tocontrol the vibration-controlling function.

Even when such damper cylinder 10 according to the second embodiment isapplied to the operator's seat supporting device 1, the same advantagesas that of the first embodiment can be obtained.

Third Embodiment

Next, FIG. 8 is a cross-sectional view showing a third embodiment of adamping function control mount cylinder.

Basic configuration of the damping function control mount cylinder(described simply as a damper cylinder 10A hereinafter) is the same asthat in the embodiment described above, but the combinatorial structureis different from that in the embodiment described above. Therefore thebasic actions and effects are the same as those described in therespective embodiments described above. It is to be noted that the samereference numerals are assigned to the same components as those in theembodiment described above and detailed description is omitted herefrom.Therefore description is made only to components having differentfunctions respectively.

The damper cylinder 10A according to this embodiment has a controlcylinder 20A incorporated in and at a central position of the bufferingcylinder 13A.

Further a coil spring 19A for restoration is provided between a mountingbase 12A provided outside the buffering cylinder 13A and attached to alower edge of the fixed member 11A and a mounting base plate 18 aprovided at an upper edge of the movable member 14A.

The buffering cylinder 13A includes the fixed member 11A having themounting base 12A and the movable member 14A sliding in the axis linedirection in the inner side therefrom, which are combined with eachother.

The fixed member 11A constituting the buffering cylinder 13A has themounting base 12A in the lower section, and in the upper section, a headmember 11 b is screwed into and fixed to an upper edge section of thecylinder member 11 a which is a main body of the fixed member 11A.

Further a lower section member 11 c is fixed to a lower edge section ofthe cylinder member 11 a, and a circular projection 15A of the movablemember 14A is slidably provided between an upper edge of the lowersection member 11 c and a lower edge of the head member 11 b, so thatthe first chamber 16 a is separated from the second chamber 16 b by thecircular projection 15A.

The movable member 14A is a tubular body slidably and coaxially engagedin the fixed member 11A, in which an upper edge section thereofprotrudes by an appropriate length from an upper edge of the fixedmember 11A, and at the top, the mounting base plate 18 a monolithicallyformed with a screwed cap 18A for supporting the supporting plate 3 isattached thereto, while a screw mounted cover 14 e is provided at thelower edge section to function as a piston and a rod.

The circular projection 15A is provided on an external peripheralsurface of the intermediate section of this movable member 14A, and aseal ring 15 b is engaged in a groove section 15 a formed on theexternal peripheral surface and contacts an internal peripheral surfaceof the cylinder member 11 a of the fixed member 11A to define a thirdchamber 16 f and a fourth chamber 16 g in the cylinder.

The control cylinder 20A is coaxially provided and engaged in themovable member 14A.

At a center of this control cylinder 20A, a supporting member consistingof a coil section 25 and the sleeve 24 a is provided with a lower edgethereof engaged in and supported by a shaft supporting hole 14 fprovided on a top surface of the screw mounted cover 14e and also withan upper edge thereof engaged in a shaft hole 14 f′ provided at a centerof a bottom surface of a supporting piece 14 h engaged in the movablemember 14A, and further a cylinder member 26A made from electromagneticsoft iron is concentrically provided outside the supporting member withboth edges thereof held by the screw mounted cover 14 e and thesupporting piece 14 h. The coil section 25 is provided at theintermediate position with the upper and lower sections thereofsupported by a non-magnetic sleeve 24 a with a slight clearance leftwith an internal peripheral surface of the cylinder member 26A made fromelectromagnetic soft iron.

A bobbin 25 a made of a magnetic material are provided at thewire-winded section of the coil section 25 so as to be the core of thewire-winded section, and a narrow clearance “a” is formed between thebobbin 25 a and an internal peripheral surface of the cylinder member26A. The lead wire 27 leading to a controller (not shown) through insideof the supporting member is connected to the coil 25 b of the coilsection 25, and a required current is fed through the lead wire 27 undercontrol by the controller.

An internal peripheral surface of the circular projection 15B protrudinginward from an internal peripheral section of the movable member 14Aslidably contacts an external peripheral surface of the cylinder member26A of the control cylinder 20A via a seal ring 15 d engaged in a groovesection 15 c provided on the peripheral surface so as to be slidable,and the third chamber 16 f and the fourth chamber 16 g partitioned inthe vertical direction by the circular projection 15B is formed betweenthe cylinder member 26A and an internal peripheral surface of themovable member 14A.

A connecting hole 14 j communicating to the first chamber 16 a and thethird chamber 16 f and a connecting hole 14 k communicating to thesecond chamber 16 b and the fourth chamber 14 g are provided above andunder internal and external circular projections 15A, 15B of the movablemember 14A, and further a connecting hole 26 a communicating to thethird chamber 16 f and the upper side chamber 22 a inside the controlcylinder 20A and a connecting hole 26 b communicating to the fourthchamber 16 g and the lower side chamber 22 b of the control cylinder 20Aare provided in the cylinder member 26A respectively.

The chambers described above are filled with a magnetic rheologicalfluid. Further seal rings are provided at an upper edge section of aninternal peripheral surface of the head member 11 b positioned on thefixed member 11A and at a lower edge section of an internal peripheralsurface of the lower section member 11 c respectively to keep inside ofthe cylinder water-tight.

The damper cylinder 10A having the configuration as described above isarranged like in the embodiment described above and is used to excitethe coil section 25 of the control cylinder 20A under control by thecontroller, and the functions are the same as those described in theembodiment above.

As for the flowing state of the magnetic rheological fluid, when themovable member 14A is pushed down, the circular projections 15A, 15Bmove downward, so that, in the buffering cylinder 13A, the fluid in thesecond chamber 16 b is pressurized and flows through the connecting hole14 k into the fourth chamber 16 g, and is further fed from this fourthchamber 16 g through the connecting hole 26 b into the lower sidechamber 22 b of the control cylinder 20A. In contrast, the first chamber16 a and the third chamber 16 f in the buffering cylinder 13A enter thereduced pressure state, so that the fluid in the upper side chamber 22 aof the control cylinder 20A passing through the connecting hole 14jflows from the third chamber 16 f into the first chamber 16 a due to apressure difference.

In the control cylinder 20A, the magnetic rheological fluid flows fromthe lower side chamber 22 b through the clearance “a” into the upperside chamber 22 a due to a pressure difference between the lower sidechamber 22 b and the upper side chamber 22 a.

With the configuration, movement velocity of the buffering cylinder 13Ais controlled by controlling a signal from a detection sensor (notshown), which is provided in the machine side against the magneticrheological fluid and detects vibrations of the magnetic rheologicalfluid passing through the clearance “a”, with the controller based ondata to feed a current at a required rate through the lead wire 27 tothe coil section 25 and generate a magnetic field corresponding to thecurrent value around the bobbin 25 a for the purpose to change fluidityof the magnetic Theological fluid to control the flow resistance.

The descriptions above assume the configuration in which two units ofdamper cylinders are employed to support an operator's seat, but thepresent invention is not limited to this configuration, and forinstance, another additional damper cylinder for supporting may beprovided in the front side or in the rear side, if necessary. With theconfiguration, even when a large load is applied to the front side orthe rear side of the operator's seat, the load can be accommodated anddampened.

1. An operator's seat supporting device for a service vehicle, whereinat least biaxially supported by damper cylinders each are arranged alongan axial line parallel to a vertical line passing through a shoulder ofan operator sitting on a seat, and the operator's seat supporting deviceincludes a posture adjusting mechanism provided by the sectionssupported by the damper cylinders and the seat.
 2. An operator's seatsupporting device for a service vehicle, wherein an operator's seat ismounted via a posture adjusting mechanism on a supporting platesupported by at least two damper cylinders at a place where anoperator's seat is installed, and at least one of the damper cylindersreduces vibrations by making use of a magnetic rheological fluid.
 3. Theoperator's seat supporting device for a service vehicle according toclaim 2, wherein, in the damper cylinder for reducing vibrations bymaking use of the magnetic rheological fluid, a buffering cylinder and acontrol cylinder for controlling vibrations with the magneticrheological fluid are monolithically formed.
 4. The operator's seatsupporting device for a service vehicle according to claim 2, whereinthe damper cylinder has a biaxial slide supporting structure, and a coilspring is provided in the inner side or in the outer side from a shaftbody having dual-shafts.
 5. The operator's seat supporting device for aservice vehicle according to claim 3, wherein the damper cylinder has abiaxial slide supporting structure, and a coil spring is provided in theinner side or in the outer side from a shaft body having dual-shafts. 6.The operator's seat supporting device for a service vehicle according toclaim 2, wherein an operator's seat rotating mechanism is provided onthe supporting plate supported by the damper cylinders.